The number of instances in which a large vessel has experienced serious difficulties during berthing operations in Duncan Bay supports the warnings published in the Sailing Directionsthat the currents in this body of water may be unpredictable and strong. When the Mandarin Arrow was approaching the pulp wharf, the tide was at its early flooding stage. One of the tugs reported that no significant current set was near the wharf; yet, a few minutes later, the Mandarin Arrow moved rapidly sideways. With a total displacement of 43510 t, a very large force would be required to move the Mandarin Arrowsideways. As there was no wind and no apparent surface current a few minutes earlier, the origin of the force was likely either a sudden surge of surface current or a subsurface current that did not affect the shallower-draught tugboats, or both. The TSB investigation into the striking of the pulp wharf by the Star Evanger cited a subsurface current as one of the probable causes leading to that occurrence. The unpredictable nature of the currents in Duncan Bay - and their effect on manoeuvring vessels - has been acknowledged by the PPA, which determined that the total accessory power available in Duncan Bay should be greater than that normally needed for berthing. The recommended accessory power level is a somewhat imprecise calculation, based on experience. As the Mandarin Arrow was only partially loaded, the available accessory power (7.4percent of the summer deadweight) was within the range considered sufficient to bring her safely alongside. However, as the tugs were not using securing lines, the actual horsepower available at any given moment was limited to that of the bow thruster and one (pushing) tug. The combined horsepower of the bow thruster and the tug on the port side was only 2770, or 5.3 percent of the summer deadweight. Furthermore, the two tugs were not designated docking tugs - one of the reasons the pilot did not secure them to the Mandarin Arrow. When the Mandarin Arrow started moving bodily towards the shore, the pilot ordered the tug from the starboard side to shift to the port side. Without any attachment to the vessel, it was the only method by which he could use this tug's power to counteract the set. The tug executed the order; however, time was lost while it moved around the stern of the Mandarin Arrow. Had there been a line from the vessel secured to the tug's bow, the latter might have started pulling the Mandarin Arrow almost immediately (if so desired) after the bridge team noticed the vessel's unwanted movement. Other countermeasures applied by the bridge team, i.e. the use of bow thruster, starboard anchor, main propulsion, and rudder, were appropriate in the existing circumstances. The tugs and the bow thruster were supposed to push the vessel against the current and away from danger. The main propulsion in the ahead mode together with (very effective) Schilling rudder in the hard-to-port position undoubtedly produced a turning force opposing the set of the current. Subsequently, the master and the pilot changed their original order and reversed the propulsion to abort the approach. At the time the propeller was reversed, the heading was approximately 240T and the vessel was swinging to port from 268T. While it is uncertain whether the ahead thrust with full port side rudder would have stopped the vessel from running aground, the attempt to abort the approach at this stage could not have produced the desired results. When it was executed, the port side was probably only about 25 m from the shoal, and the distance was closing. The Mandarin Arrowgrounded and the engine was stopped at 0540:57; it had been running astern for approximately two minutes, and at full power for only part of that time. Even if the vessel had had no forward motion, it would have taken more time for the astern thrust to overcome her mass, accelerate, and pull astern. The athwartships momentum continued during this time, and the vessel closed the distance to the rocky shoal faster than the reversed propulsion could move her past the shoal. Additionally, the right-handed propeller in the reverse mode produced, at the stern, a lateral thrust to port that augmented the existing sideways motion. The immediate post-accident orders and undertakings by both the crew and the authorities were appropriate in the circumstances. In its evaluation of the berthing conditions in Duncan Bay, the PPA studied this occurrence and 22similar occurrences. The PPA subsequently made a number of recommendations which, if implemented, are likely to improve berthing conditions in Duncan Bay.Analysis The number of instances in which a large vessel has experienced serious difficulties during berthing operations in Duncan Bay supports the warnings published in the Sailing Directionsthat the currents in this body of water may be unpredictable and strong. When the Mandarin Arrow was approaching the pulp wharf, the tide was at its early flooding stage. One of the tugs reported that no significant current set was near the wharf; yet, a few minutes later, the Mandarin Arrow moved rapidly sideways. With a total displacement of 43510 t, a very large force would be required to move the Mandarin Arrowsideways. As there was no wind and no apparent surface current a few minutes earlier, the origin of the force was likely either a sudden surge of surface current or a subsurface current that did not affect the shallower-draught tugboats, or both. The TSB investigation into the striking of the pulp wharf by the Star Evanger cited a subsurface current as one of the probable causes leading to that occurrence. The unpredictable nature of the currents in Duncan Bay - and their effect on manoeuvring vessels - has been acknowledged by the PPA, which determined that the total accessory power available in Duncan Bay should be greater than that normally needed for berthing. The recommended accessory power level is a somewhat imprecise calculation, based on experience. As the Mandarin Arrow was only partially loaded, the available accessory power (7.4percent of the summer deadweight) was within the range considered sufficient to bring her safely alongside. However, as the tugs were not using securing lines, the actual horsepower available at any given moment was limited to that of the bow thruster and one (pushing) tug. The combined horsepower of the bow thruster and the tug on the port side was only 2770, or 5.3 percent of the summer deadweight. Furthermore, the two tugs were not designated docking tugs - one of the reasons the pilot did not secure them to the Mandarin Arrow. When the Mandarin Arrow started moving bodily towards the shore, the pilot ordered the tug from the starboard side to shift to the port side. Without any attachment to the vessel, it was the only method by which he could use this tug's power to counteract the set. The tug executed the order; however, time was lost while it moved around the stern of the Mandarin Arrow. Had there been a line from the vessel secured to the tug's bow, the latter might have started pulling the Mandarin Arrow almost immediately (if so desired) after the bridge team noticed the vessel's unwanted movement. Other countermeasures applied by the bridge team, i.e. the use of bow thruster, starboard anchor, main propulsion, and rudder, were appropriate in the existing circumstances. The tugs and the bow thruster were supposed to push the vessel against the current and away from danger. The main propulsion in the ahead mode together with (very effective) Schilling rudder in the hard-to-port position undoubtedly produced a turning force opposing the set of the current. Subsequently, the master and the pilot changed their original order and reversed the propulsion to abort the approach. At the time the propeller was reversed, the heading was approximately 240T and the vessel was swinging to port from 268T. While it is uncertain whether the ahead thrust with full port side rudder would have stopped the vessel from running aground, the attempt to abort the approach at this stage could not have produced the desired results. When it was executed, the port side was probably only about 25 m from the shoal, and the distance was closing. The Mandarin Arrowgrounded and the engine was stopped at 0540:57; it had been running astern for approximately two minutes, and at full power for only part of that time. Even if the vessel had had no forward motion, it would have taken more time for the astern thrust to overcome her mass, accelerate, and pull astern. The athwartships momentum continued during this time, and the vessel closed the distance to the rocky shoal faster than the reversed propulsion could move her past the shoal. Additionally, the right-handed propeller in the reverse mode produced, at the stern, a lateral thrust to port that augmented the existing sideways motion. The immediate post-accident orders and undertakings by both the crew and the authorities were appropriate in the circumstances. In its evaluation of the berthing conditions in Duncan Bay, the PPA studied this occurrence and 22similar occurrences. The PPA subsequently made a number of recommendations which, if implemented, are likely to improve berthing conditions in Duncan Bay. The Mandarin Arrow grounded while approaching a berth in Duncan Bay when a current suddenly set her to the east and off the planned path. The currents in Duncan Bay have been known to cause berthing difficulties in the past. Currents in the Duncan Bay area do not follow a pattern that allows for accurate prediction. In 1993 the PPA recommended that vessels berthing in Duncan Bay have available accessory horsepower 50 percent greater than that normally required for docking and undocking in other berthing circumstances. The tugs assisting the Mandarin Arrow were not designated docking tugs and were used in the pushing mode only. The abort manoeuvre was initiated too late to have the intended result of withdrawing the vessel from danger. The Mandarin Arrow sustained extensive damage to her shell plating.Findings The Mandarin Arrow grounded while approaching a berth in Duncan Bay when a current suddenly set her to the east and off the planned path. The currents in Duncan Bay have been known to cause berthing difficulties in the past. Currents in the Duncan Bay area do not follow a pattern that allows for accurate prediction. In 1993 the PPA recommended that vessels berthing in Duncan Bay have available accessory horsepower 50 percent greater than that normally required for docking and undocking in other berthing circumstances. The tugs assisting the Mandarin Arrow were not designated docking tugs and were used in the pushing mode only. The abort manoeuvre was initiated too late to have the intended result of withdrawing the vessel from danger. The Mandarin Arrow sustained extensive damage to her shell plating. The vessel grounded as a result of being set suddenly onto a shoal. Contributing to the occurrence was the fact that, at this stage of the tide, currents in the area are unpredictable, the manoeuvres to withdraw the vessel from danger were undertaken too late to have the intended result, and the assisting tugs were not of a design well suited to assist in the docking of this large vessel.Causes and Contributing Factors The vessel grounded as a result of being set suddenly onto a shoal. Contributing to the occurrence was the fact that, at this stage of the tide, currents in the area are unpredictable, the manoeuvres to withdraw the vessel from danger were undertaken too late to have the intended result, and the assisting tugs were not of a design well suited to assist in the docking of this large vessel. In October 1999 the PPA's Safety and Operational Review Committee reevaluated the issue of berthing difficulties in Duncan Bay and made several recommendations: simulator training specifically addressing the Duncan Bay area and conditions; an increased number of apprenticeship trips into Duncan Bay; review of the currency and familiarization trips into Duncan Bay; evaluation of the usefulness of current meter(s) in Duncan Bay; assurance that two suitable twin-screw docking tugs are available; and the placing of leading lights (ranges) along the wharf face as a guide to berthing vessels. Additionally, the PPA emphasizes BRM principles and reminds its pilots to ensure that masters are made aware of both the planned approach and an alternative abort plan. Furthermore, the PPA advises that information available to pilots should be shared with shipping companies in order that vessel navigation personnel can be fully informed in advance of a trip of any special circumstances pertaining to their intended passage. In March 2000 the Duncan Bay simulation was completed and training commenced for both senior and apprentice pilots on the full-mission bridge simulator at Star Centre in Dania, Florida, USA.Safety Action In October 1999 the PPA's Safety and Operational Review Committee reevaluated the issue of berthing difficulties in Duncan Bay and made several recommendations: simulator training specifically addressing the Duncan Bay area and conditions; an increased number of apprenticeship trips into Duncan Bay; review of the currency and familiarization trips into Duncan Bay; evaluation of the usefulness of current meter(s) in Duncan Bay; assurance that two suitable twin-screw docking tugs are available; and the placing of leading lights (ranges) along the wharf face as a guide to berthing vessels. Additionally, the PPA emphasizes BRM principles and reminds its pilots to ensure that masters are made aware of both the planned approach and an alternative abort plan. Furthermore, the PPA advises that information available to pilots should be shared with shipping companies in order that vessel navigation personnel can be fully informed in advance of a trip of any special circumstances pertaining to their intended passage. In March 2000 the Duncan Bay simulation was completed and training commenced for both senior and apprentice pilots on the full-mission bridge simulator at Star Centre in Dania, Florida, USA.